I will return
by ANNAFLORINDA
Summary: Based on the ending of 1x08. Mattie confesses her feelings for Leo in the warehouse, but a year later, everything has changed, or has it? Will Leo and Mattie get the happy ending they both secretly want? Leo/Mattie
1. Chapter 1: Passionate kisses

**I do own Humans. Spoilers for 1x08. Please, read and review:). Based on the end of 1x08 and then will go AU from there. Enjoy:). Leo/Mattie, Mattie/OC**

 **Chapter 1: Passionate kisses.**

In the dark warehouse, Mattie did a lot of thinking and the one thing, the one person who dominated her thoughts was Leo. When their house had been attacked and he and the others had been taken away, all of the quiet conversations which the two of them had shared had made far more sense. Mattie had no idea if Leo was aware of the connection they had, but she did know that she did not want him to leave without him knowing how she felt about him and she was sure that he felt the same way about her.

Leo, Mia, Max and Niska had decided that they could not risk to take Fred with them, as he could endanger all of them and Niska decided that she wanted to live her own life. She hugged Mia and Max goodbye, then turned to Leo, who was standing in silence, looking very saddened by her departure. They rested their heads together, in a way of affection, then Niska walked away and closed the door. Mattie knew that this was her chance and that it was now or never, as she knew that Leo was never going to admit his feelings for her, he may not even have worked them out yet.

"Leo." She stepped forward and found that all eyes were on her, but her dad did not look surprised; he had caught one of their conversations in the kitchen the other day and had sensed that there was an attraction between them. When Leo gave her a questioning and rather embarrassed look, she said, "Leo, I know this isn't the best time, but when you were kidnapped, I realised something. I realised that I could loose you without ever telling you how I felt. And now you're leaving again, so this is my chance to tell you-if I don't now I never will."

Smiling softly, Leo reached out for her hands and squeezed them. In a gentle tone, which was uncharacteristic, he remarked, "Mattie, I know what you're going to say… I've felt it too. But how could we make it work? You and I, I mean? I'm not whole and you deserve somebody who is, Mattie, and I can't give you the love you need."

Mattie threw her head back and pulled her hands away in frustration. "I don't want to be with anyone-I want to be with you! Don't you get it? I've never done anything like this before and me even admitting my feelings toward anyone is a massive personal step for me-as I'm sure it is for you, after everything you've been through." Out of the corner of her eye, she saw Mia smiling and she knew that she had her approval.

"But everything I've been through has taught me never to let people get close to me," retorted Leo, in his usual gruff tone, "if I get close to people, or let them in, they end up betraying me… or dying. I can't take that risk, Mattie. I can't let you in you deserve better than me. It wouldn't work." His blue eyes met hers and they stood there in silence for a couple of seconds, before Mattie acted impulsively and kissed him passionately. Much to her surprise, Leo kissed her back and they wrapped their arms around each other, holding each other close, closing their eyes, forgetting that there were others in the room. As their kiss ended, they opened their eyes and rested their heads against the head of the other. They were both crying, as the emotion and the passion in the kiss which they had just shared was beyond anything either of them had ever experienced in their entire lives. Leo cupped her cheek with his hand and, stroking it, whispered, "I will return, Mattie, I promise." With that, he and the others turned to leave the warehouse, leaving Mattie feeling conflicted and her family stunned.


	2. Chapter 2: Some things have changed

**I do own Humans. Spoilers for 1x08. Please, read and review:). Based on the end of 1x08 and then will go AU from there. Enjoy:). Leo/Mattie, Mattie/OC.**

 **Chapter 2: Some things have changed.**

A year passed and still Leo and the others had not returned. Mattie had decided that there was no point in waiting for Leo to return, so she had started a relationship with a boy named Jack Snow. The two of them were at university together and they had a great deal in common, but no matter how perfect he was, he was not Leo and that thought haunted Mattie every time she saw her boyfriend or kissed him-she was thinking of Leo. On the evening of her first anniversary with Jack, her parents were out, Toby was out with his friends and Sophie was at a sleepover, so Mattie and Jack had the house to themselves. Mattie knew that he was knee to consummate their relationship, but she was not ready and he respected that.

"Have you made dinner?" she asked, walking into kitchen. "I thought we were going to play CandyCrush?"

Jack laughed, nodding. "Yes….Erm, before dinner, there's something I would like to talk to you about-well, more ask you, actually." He sounded very nervous and Mattie felt apprehensive as she walked over to the table and sat down. "Matilda, we've been together for a year now and the day we met will always stay with me. I mean, I can't believe that I was being so stupid with that computer system." They both laughed at the memory, as it was the first time they had met and they had started to date after that. "And that first time I saw you, I knew that you were-well-the one. Matilda, I love you-I know we haven't exchanged those words yet, but I do with all my heart. Matilda Hawkins, will you marry me?"

Mattie stared at him for a couple of seconds, before asking, "How soon are you expecting an answer?"

The smile fell slightly from Jack's face, but he recovered it and replied, "Well, take as much time as you need, my dear. I wouldn't want to rush you into anything." He stood up and placed the box on the table. There was a deadly silence, then he said, "I'm going to go out to… get some milk. I'll be back soon." He kissed her gently on the cheek, before picking up his jacket and leaving the house. Mattie's hands reached out to the velvet box and her fingers traced the box, but she could not bring herself to open it. She knew that she could not wait for Leo to return, but it would also not be fair on Jack to marry him when he was her second choice.

Her thoughts were interrupted by a knock on the door. Mattie sighed, thinking that it was Jack and she opened the door and saw that it was not Jack, but Mia… and Leo. Her heart almost stopped and their eyes met. She pulled Mia into a hug, more for something to do than anything else. She looked up at Leo and hissed, "Where the Hell have you been for a year?"

Leo stared at her, almost in shock, but it was Mia who answered as they walked into the house. "We were separated and almost destroyed, Mattie. We didn't stay away for a year out of choice." She looked around the house and asked, "Where are your parents? Are you here with someone?"

Looking Leo in the eye, Mattie nodded. "Yeah, my boyfriend, actually."

Mia forced a smile and asked her how she had met him. As Mattie gave Mia all of the details about her relationship with Jack, Leo walked past them and into the kitchen. There, he saw the box with the engagement ring in it. With shaking hands, he opened it and saw a diamond ring in there. His breath began to speed up and he felt tears burning his eyes. Why had she not waited for him and had she accepted this man's proposal? Mattie and Mia walked into the kitchen and Leo handed the former the box, showing the ring. In a dark voice, he asked, "Have you accepted?"

Mattie stared down at the ring. "No, I haven't."

Sighing, Leo hissed, "How can you even be considering accepting him, Mattie? I mean, do you really love him? I knew this would happen-when I let people in, they always betray me!"

"I didn't betray you, you left!" Mattie began to shout and she saw the shock in Mia's eyes. "I've gone for a year of no contact from you-not so much as a single text or email, so forgive me if I've moved on with my life, Leo, but I didn't have a choice. If you have ever really cared about me, let me get on with my life."

"Mattie, you were the one who approached me in the warehouse. You were the one who initiated the kiss!" Leo retorted, in an equally angry tone. Mattie's retort was halted by the arrival of Jack. He asked who Leo and Mia were, but before Mattie could explain, Leo walked past her and walked out of the house. Mia passed Mattie something on a piece of a paper, before hugging her and leaving the house.

"Who the Hell were they?" Jack demanded.

Mattie looked down at what Mia had given to her and realised that it was Leo's new number. "They were friends," she inhaled a deep breath, then turned to face him, "about the proposal, Jack, I have to decline. I'm sorry and I think that we should stop seeing each other. This was a mistake." She handed him back the box, kissed him goodbye and went upstairs to her bedroom. Mia had not only given her Leo's number, but she had also given her some kind of memory stick and Mattie wondered why. Placing it in the draw, she turned off her lights and went to bed, hoping that her thoughts would have more clarity in the morning.


	3. Chapter 3: Realisation

**I do not own Humans. Please, read and review:)**

 **Chapter 3: Realisation.**

The next morning, Mattie awoke early and turned on her laptop. She rummaged in her draw and inserted the memory stick into it, wondering what it could be and why Mia had given it to her. Why had she given it to her then and not before? Just as she was about to open up the file, the door opened, hr parents walked in and Mattie closed her laptop and put it to her side, so that they would have no idea what she was looking at.

"So, how was last night?" Her mum asked, as she sat down on the bed and rubbed her daughter's hair.

Mattie considered whether to tell her parents or not, before answering, "Well, Jack proposed to me."

Her parents' faces lit up with pride and happiness, they offered their congratulations and her mum asked to see the ring. In response, Mattie held up her hand, showing them that there was no ring, hoping that they would understand and not ask her any questions-wishful thinking that was!

Joe was the first one to recover the art of speech and he asked, "Why did you refuse him? I mean, I thought you were happy with him?"

Mattie sighed. "Yeah, I was, but I don't love him and I only want to marry somebody I love. You can understand that, can't you? I gave him my answer last night and that's the final answer I will give him."

"So, if he were to propose say next year, would you have a different answer?" Laura asked, in a hopeful tone. Rolling her eyes, Mattie snapped, "You're not listening, Mum! I used the past tense when I said that was I was happy with him-I refused his proposal and I ended our relationship. He won't propose again and I don't want him to."

"Mattie, why do you have to be so extreme?" Joe asked, before glancing at his wife and adding, "Mattie, is this to do with Leo? Honey, you can't spend your life waiting for him to come back and, even if he did, it wouldn't work out between the two of you. He's half-Synth, half-human and he's had a very troubled life… it wouldn't work. You can't keep holding onto a fantasy." Mattie stared at him, her eyes not giving away any of the emotions she was feeling. What right did he and her mum have to cast judgement on Leo, they didn't really know him, not in the way she did? She pulled her laptop back on her knee and her mum and dad understood and left, closing the door behind themselves.

As soon as she was sure that they had gone, she opened the file and saw that it was somebody's memories: Leo's memories over the past year. The file showed the memories which he had thought about the most over the past year: the death of his mum and the kiss he and Mattie had shared in the warehouse. With her fingers shaking, Mattie clicked on one of her most precious memories and watched it, through Leo's eyes. As the memory reached the time when they kissed, she felt tears threatening to fall from her eyes as watching it in this way made her realise how strong her feelings for Leo had been, how strong his feelings had been for her and it made her think of how terrible he must have felt when he had seen Jack's engagement ring, which had been intended for her.

Mattie spent most of the day in her bedroom, but in the evening, she went downstairs and was amazed to see Mia, Max and Fred there. Her eyes scanned the room for Leo, but he was not there. "Where's Leo?" she asked.

Mia walked over to her, looking very worried. "He's on a mission and we need your help, Mattie. Can you hack into the tunnel map underneath the science block?" Mattie nodded. "Good, you'll need this to communicate with Leo. He's down there now." She handed Mattie a radio and she could feel her hands shaking.

Opening up her laptop, Mattie placed it down on the table and began to hack in. She was very aware that her family were watching her as well as Mia, Max and Fred. Once the hack was complete, she looked to Mia, who nodded and she picked up the radio and spoke into it, "Leo? Are you there? I've hacked into the system."

" _I knew you could do it_." Leo's voice came from the other side. " _So, which way do I go?_ " Mattie began to guide him to the exit point and her family stood around the laptop along with Mia and Fred, but Mattie remained focused on and ignored them. Leo's position was on the screen and they all smiled as they saw that he was near the exit. Mattie picked up the radio and told him, "Take the next left and you'll be out."

She could hear that Leo was smiling by the way he spoke. " _Thanks_." However, their relief was short-lived as Mattie saw that he was being followed. "Leo, you're being followed-you have to get out of their now!" She could see the panic and she could hear Leo moving very quickly. Panting, he spoke into the radio, " _If they trace this, it could put you all in danger. I have to break radio contact._ "

Mattie shook her head in distress, "No. Don't you dare! I've already lost you once, I'm not doing it again!" There was a dead silence and she became worried that he had broken their contact. "Leo!" she shouted, with tears in her eyes; the thought of loosing him again was unbearable. She felt a hand on her shoulder and she knew that it was Mia, who was just as scared as she was.

The radio made a sudden noise, indicating that it was indeed on and that Leo was still there. " _Mattie, are you there_?"

Nodding, Mattie replied, "Yes, I'm here. Are you ok?"

There was a loud bang and Mattie closed her eyes, not wanting to look at her screen. Just then, Leo's voice came through very clearly, as he cried, " _Mattie, I love you._ "

Without thinking, Mattie whispered into the radio, "I love you too. I always have and will." The radio went dead and there was complete silence. Mattie let out some sort of cry and buried her face in her hands, allowing herself to cry. Her mum wrapped her arms around her and Mia whispered, "He'll be ok and he will come back, Mattie. I know he will." Mattie buried her head in her mum's arms, not quite able to comprehend that she had spoken those words to someone whom she may never see again, but she knew that it was right. She did love Leo and there was no point in denying it and, if she were never to see him again, she knew that he knew that now.

They all decided to go bed, as there was little more they could do and they would do more in the morning, after a good night's sleep. Mattie picked up the radio and laid it on her nightstand, as she tried to sleep. She next awoke at sunrise and she heard sound coming from the radio. Holding it close to her, she heard that it was Leo and he was whispering the name she had gone by on line, the first time they had met. Mattie stated his user name in, wondering where he was now. Her question was answered when there was a knock on the door. She jumped up and ran downstairs, opening the door. It was him and they ran into each other's arms before their eyes met and they kissed passionately. Smiling and whispering that they loved each other, they made their way to Mattie's bedroom. Later, they lay together, with their faces next to each other, sleeping, finally peaceful for the first time.


	4. Chapter 4: Marriage and trials

**I do not own Humans. Please, read and review . Warnings: brief mentions of a miscarriage.**

 **Chapter 4: Marriage and trials.**

Mattie graduated university at 21, but stayed on to do a Phd for another four years. On that graduation day, when she was 25, Leo took her aside from everyone else and asked her to marry him. With tears in her eyes, she kissed him, her acceptance being in the love she showed. The two of them married that December, in the snow, vowing to love the other for the rest of their lives and they knew that they indeed would. A year later, they decided to start to try to have a baby, as it was something which they both wanted. However, after 6 months of trying and no success, Leo decided to go to see a doctor.

Mattie was working in the kitchen, waiting for her husband to return. The front door opened and Leo walked in. Without saying anything he pulled Mattie into a tight hug and held her to his chest, in need of the comfort. He finally sat down and Mattie asked, "What did the dr say, Leo?"

Looking down at the table, he replied, "He-he said that we probably won't be able to have children, because of me-how I'm made. I'm so sorry, Mattie." He bit his lip. "He did say that we could try IVF…"

"Then let's do that," Mattie said, sounding very determined, "we're not going to give up. And this is not your fault. Whatever happens, we'll face this together. Understand?" She knew that Leo was insecure about their relationship, not because of their marriage, but because of everything he had experienced. Leo nodded, forcing a smile and he kissed her gently, which she returned.

A couple of months later, after using IVF because of Leo's problems, Mattie was told that she was pregnant. She made her way home to tell Leo and he was over the moon with joy and they kissed and hugged. They agreed not to tell anyone, until she was past 12 weeks, but the happiness which they both felt was like nothing they had ever experienced before. However, this happiness was short-lived when Leo woke up to see his wife bleeding. She was rushed to the hospital and their worst fears were confirmed: she had lost the baby. They held each other close and Leo promised her that he would not put her through anything like that again, as he did not want to risk losing her and Mattie agreed. They began to plan their lives without children, but Mattie was secretly still trying to conceive.

A year later, her doctor informed her that she was 3 months pregnant. She made her way home to tell Leo, beaming. "Leo, I have something to tell you." He looked up from his paper, looking curious, "What is it? Have you got that promotion you wanted?"

Mattie shook her head. "No, even better. I'm 3 months pregnant and passed most of the danger zone." A shocked look fell upon Leo's face. Smiling, he walked over to her and hugged. "How did that happen? I mean, I thought it couldn't be done."

Biting her lip, Mattie sighed. "Please, don't be mad, but ever since we lost the other baby, I've been trying to get pregnant again. I know I should have told you, but I didn't want you to be upset if it didn't work." Instead of shouting at her, as she had assumed he would, Leo leaned forward and kissed her, with love and happiness in his eyes. "I'm so happy. We may finally get the family we want. Have you told your parents?"

They spent the next hour or so ringing their respective families, telling them all the good news; Mattie called her parents, Toby and Sophie and Leo called Mia, Niska, Fred and Max. They were all overjoyed by the news and Laura and Joe were thrilled at the idea of being grandparents. Mattie and Leo had not told them about Mattie's miscarriage a year ago, but they had suspected that something of that nature had occurred and they were so happy that their daughter and son-in-law had a chance at this happiness.

A couple of months later, Leo drove himself and Mattie to the hospital. They were going to have a scan, to check how the baby was and, if they so desired, to find out the sex of the baby. Leo insisted that he wanted it to be a surprise, but a part of Mattie wanted to know, but she did not want to know if Leo did not know. As they walked into the hospital, Mattie asked, "Why do you not want to know the sex of the baby?"

Leo sighed and replied, "Well, call me as pessimist, but I don't want to know until we're certain that everything's ok. I know it sounds stupid, but it makes sense, doesn't it?" He turned to face Mattie and found that she was smiling. She cupped his face with her hand and kissed him gently for a moment, before taking hold of his hand and leading him to the waiting room.

The doctor led them into the room a couple of minutes later and Mattie laid herself down on the bed, whilst Leo sat next to her, holding her hands, praying that everything was alright. Everything was alright, in fact, the doctor informed them that Mattie was carrying twins. She asked Leo and Mattie if they wanted to know the sex of the babies, but they both said 'no' at the same time, so she nodded. Mattie sat up and pulled Leo into a tight embrace, relief that their babies were alright filling their bodies and the shock that they were going to have two children.

Months later, when Leo was playing football with Joe, Toby, Fred and Max, Mia called him, telling him that Mattie was going into labour. She told her surrogate son that she and Niska would take Mattie to the hospital and meet them there. Leo thanked her, before saying, "Mattie's having the babies." Joe and Toby stared at him for a second, before running into the house, shouting for Laura and Sophie. "Why are you shouting, Dad?" Sophie asked as she and her mother came downstairs.

In a happy and nervous voice, Leo answered, "Mattie's going into labour. She's going to have the babies. Come on!" They all rushed to the car, but Joe found that he was too stunned to drive, so his wife drove instead, saying that they were not going to miss the birth of their first grandchildren.

Once at the hospital, they found Mattie's room. Leo ran over to her and hugged her, before asking Mia how far along she was. Mattie's family entered behind Leo and hugged her. The doctor walked in and the labour began. The first baby started to come out quickly and Mattie squeezed her husband's hands in both anticipation and pain. The cry of the baby was all they needed to know that he or she was alright and Leo allowed his first tears of joy to fall. "Is-is it ok?" he asked, as the doctor examined the baby.

"Yes, it's fine. It's a baby boy, by the way." Baby number one was passed to the nurse to be wrapped up. Leo and Mattie wanted to hold their son, but Mattie knew that she had to get the other baby out soon. The second baby took half an hour, but eventually, it came out and was in the doctor's arms, crying. Throwing her head back in relief, Mattie asked, "Is it ok?"

Wrapping the baby up in a blanket, the doctor answered, "Yes. Congratulations-you have two beautiful baby boys, Mr and Mrs Elster." The first baby was wrapped up in a blue blanket and second in a green one. Each was passed to one parent and Mattie and Leo held their sons, speechless with tears in their eyes.

Mia was the first to move, kissing both of the babies on the head, then kissing Leo and Mattie in the same place. Laura stepped forward and kissed her daughter on the head, stroking the check of her grandson who was in the arms of her daughter. Sophie bounded over to Mattie's side, pulling Niska along with her. "Matts, what are you going to call them? They're boys-do you and Leo have names?"

"How about David, after your father?" The happy family looked up to see Dr. Milligan standing in the doorway. He walked into the hospital room, smiling at the sight of the new family. "He was your father, Leo, and he loved you very much. Why not honour him by naming one of his grandsons after him?"

Leo looked down at his sleeping son in his arms and then at Mattie. She nodded and resolved, "Ok, the one in your arms is David. David Thomas Elster and this one"- she smiled down at the sleeping baby in her arms smiling, -"will be Samuel Max Elster. How does that sound?" In response, Leo smiled and kissed her briefly, before replying, "It's perfect, Mattie."

Mia smiled and asked, "May I hold David? I mean, he is kind of my grandson too."

"And our nephews." Max and Fred said at the same time. Leo's eyes flew to Niska. Years ago, she had dismissed such terms as 'human words' but as she looked at the two babies, her eyes began to soften. She walked over to David in Leo's arms and kissed him on the head. "And mine too." She whispered, wrapping an arm around Leo and hugging him.

Smiling, Leo passed David to Mia and Mattie passed Samuel to her mother and father, who held the baby together in their arms. With the babies in their arms, Leo and Mattie turned to each other and wrapped their arms around each other, kissing and holding the other close, happy with the lives which they had created together


	5. Epilogue

**Final chapter is here! Enjoy and please review:)**

 **Epilogue: 5 years later…**

5 years later and the Christmas bells rang. Laura and Joe were hosting the Hawkins-Elster family Christmas dinner, which included humans as well as Synths. Leo and Mattie were the first to arrive. David and Samuel, who were now 5, threw down their hats and ran over to their grandfather and then to their Uncle Toby and the four of them played a game in the living room. Leo and Mattie's daughter slipped out of her dad's arms, hugged him and then ran over to Sophie. The elder girl led her up to her bedroom to play with her old Barbie dolls. She was named Beatrice after Leo's mum. She was 3 years old and the spitting image of her mum, but she did have her dad's blue eyes. Beatrice- or 'Bea' as she was known- had been born two years after the birth of her brothers and Leo and Mattie had been overjoyed with having another child. They had not decided on a name, but she had been born on Leo's mum's birthday, so they had decided to name her after her grandmother. Laura led her daughter into the kitchen, as Leo took off his coat and scalf. "So, are the boys and Bea looking forward to Christmas?"

"Oh my goodness, yes!" Mattie smiled. "How did you and Dad cope with the three of us? Leo and I struggle sometimes. David and Sammy got into a snowball fight. I hate to say it, but they are so much like me!" She laughed and her mum laughed too.

Laura paused, before asking, "Have you heard about Toby's new girlfriend?" Laughing, Mattie nodded. "Yes, I have. What are the odds that this one will last more than two months? He should be settled down by now." Her mum shook her head and murmured, "I'm glad that you're happy, Matts. I never thought that you'd become this carer woman, happily married with three children, but you are and I'm proud of you."

"Thanks, Mum." They hugged, then her mum left to go and sort out the presents in the living room. Mattie felt arms wrap around her and she knew that it was Leo. Turning around to face him, she asked, "Are the others on their way?"

Smiling, Leo nodded. "Yes, they are on their way, my darling."

"Don't call me that!"

"Sorry. It's just-I've never been happier." Leo sighed. "I have everything I've ever wanted: a family. A loving wife, great kids, brothers, sisters… and if it weren't for you, I'd be lost." Mattie rested her head against his and whispered back, "I was lost before I met you, Leo. I didn't know who I was and I didn't know the meaning of true love-I didn't even think that happy endings existed. But now I know they do." They raised their heads, then kissed passionately, before running out into the snow with their sons. Bea and Sophie came out to play too and Leo picked up his daughter and swung her around in the air as she giggled.

It was a pretty picture of a family and it was what they had all wanted all along.


End file.
